The present invention relates to a data access device and an access error notification method.
To improve an access performance, an access method is sometimes used, which executes speculative load for a bus slave, such as a RAM (Random Access Memory). With regard to an error detected in the bus slave in an access to the bus slave, it is possible to immediately notify an error processing unit or the like of that error by the bus slave. However, in a case where that access is a speculative access, it may be necessary to refrain from error notification to the error processing unit or the like. Regarding this, U.S. Pat. No. 5,864,692 states that, with regard to an error occurring in a process in association with a speculative instruction, the error should not be reported before it is determined whether that instruction is actually necessary.
For example, for speculative load, acquired read data may become invalid because of cancellation of a branch or the like due to a failure of prediction. In this case, it is necessary to prevent notification of an error detected in a bus slave for a load access. As a configuration for achieving this, a configuration can be considered in which, when an error has occurred in association with speculative load, a bus slave notifies a bus master of occurrence of the error without immediately notifying an error processing unit or the like of the error, and the bus master performs error notification at a time when it is fixed the speculative load is necessary.
That is, with regard to an error in an access that is not speculative, the bus slave is required to perform error notification and, with regard to an error in a speculative access, the bus master is required to perform error notification.